It is widely known that olefin polymerization processes utilizing bulky ligand transition metal catalysts, otherwise known as metallocene catalysts, have produced a diverse array of new polymers which are useful in a wide variety of applications and products.
A well known problem associated with the use of metallocene catalyst systems is their tendency to cause fouling and/or sheeting in gas phase and slurry polymerization processes. Fouling on the walls of the reactor and/or reactor components results in many serious problems including poor heat transfer, particle morphology, and reactor shut-down.
In an effort to solve these problems, many catalyst system modifications and modifications to the polymerization conditions have been reported. For example, U.S. Pat. Nos. 4,792,592; 4,808,667; 4,855,370; 4,876,320; 4,978,722; 5,026,795; 5,034,481; 5,037,905 are all directed toward the use of antistatic agents or other additives.
While these approaches may reduce fouling or sheeting somewhat, they are not generally useful with all catalyst systems, they may be expensive to employ, and they may not reduce both fouling and sheeting to a level sufficient for the successful operation of a continuous process, particularly a commercial or large-scale process. Thus, it would be highly advantageous to have an improved metallocene catalyst system that in a polymerization process would significantly enhance reactor operability by reducing both fouling and sheeting.